Heinz M, Schäfer K, Braun H A
Institut für Zoophysiologie, Universität Hohenheim, Stuttgart, F.R.G.
Brain Res. 1990 Jun 25;521(1-2):289-95. doi: 10.1016/0006-8993(90)91554-t.
Afferent activity of single facial cold receptors was extracellularly recorded from infraorbital nerve fibers in the rat, and the response properties of 28 receptors to thermal stimulation were quantitatively studied. Generally, on repeated stimulation, the afferent activity was highly reproducible and was not dependent on previous adapting temperatures. At constant temperatures, a periodic pattern was apparent in the discharges of 24 receptors; in the remaining 4 receptors periodic elements could not reliably be detected. The temperature dependence of the cyclic pattern corresponded to that observed in other mammalian cold receptor populations: we observed regular impulse groups (bursts) at lower and beating activity at higher adapting temperatures. Rapid changes of temperature induced transient alterations of activity. The dynamic response to cooling was biphasic, indicating a complex sequence of receptor events. A transient acceleration of impulse frequency was followed by a dynamic burst discharge which was characterized by longer pauses and a greater number of impulses per burst compared with the steady-state activity at the same temperature. This indicates a deceleration of the periodic receptor events during the adaptation process following dynamic responses, which is accompanied by a concomitant shift of these processes to a more pronounced suprathreshold condition. In an additional series of experiments, parameters of the periodic activity in the rat were compared with corresponding data of facial and lingual cold receptors in the cat. Whereas the number of impulses per cycle was similar in the 3 receptor populations, the frequency of the periodic pattern proved to be considerably higher in the rat than in the cat.
从大鼠眶下神经纤维细胞外记录单个面部冷感受器的传入活动，并对28个感受器对热刺激的反应特性进行了定量研究。一般来说，在重复刺激时，传入活动具有高度可重复性，且不依赖于先前的适应温度。在恒定温度下，24个感受器的放电呈现出周期性模式；在其余4个感受器中，无法可靠地检测到周期性元素。这种周期性模式的温度依赖性与在其他哺乳动物冷感受器群体中观察到的情况一致：我们在较低适应温度下观察到规则的冲动群（爆发），在较高适应温度下观察到跳动活动。温度的快速变化会引起活动的短暂改变。对冷却的动态反应是双相的，表明感受器事件的序列复杂。冲动频率的短暂加速之后是动态爆发性放电，与相同温度下的稳态活动相比，其特征是停顿时间更长，每次爆发的冲动数量更多。这表明在动态反应后的适应过程中，周期性感受器事件减速，同时这些过程向更明显的阈上状态转移。在另一系列实验中，将大鼠周期性活动的参数与猫面部和舌部冷感受器的相应数据进行了比较。虽然这3个感受器群体每个周期的冲动数量相似，但大鼠周期性模式的频率被证明比猫高得多。
